Sheet metal nibbling tool



March 31, 1942. c. B. GRAY SHEET METAL NIBBLING' TOOL Filed May 1, 1940CHARLES B. GRAY $7 Patented Mar. 31, 1942 UNITED STATES PATENT OFFICESHEET METAL NIBBLI'NG TOOL I Charles B. Gray, Millbourne, Pa.

Application May 1, 1940, Serial No. 332,658

(Cl. so -22s) 11 Claims.

This invention relates to a metal cutting tool and more particularly toan improved construction of portable, hand-held sheet metal cutting toolof the nibbler type.

It is among the principal objects of the present invention to provide asmall, portable and compact nibbling tool adapted to be hand-held forconvenience of operation and to facilitate moving of the tool relativelyto and about the work to be cut, the tool being provided with arelatively fixed die with which coacts a reciprocating punch or cuttingtool whereby as the tool is fed to and through the work to be cut thepunch and die coact to rapidly cut out of the sheet metal and along agiven line a successive series of chips or slugs to form a slot in thework.

A further and important object of the invention is to provide a portablenibbling tool of the character above described with a relatively fixeddie which is so associated with respect to the reciprocating punch andwhich is of such design as to enable the tool to be readily turned ineither direction about the reciprocating axis of the punch to facilitatethe cutting of curved slots and other irregular designs in the sheetmetal.

Still another object of the invention is to provide a portable hand-heldnibbling tool of the character described wherein the relatively fixedsupport for the die serves in itself as a pilot or feed-limiting memberfor limiting the feed of the stock as the nibbling tool cuts a slottherein, the said pilot portion of the support for the die beingdesigned not only to facilitate cutting of slots along curved orirregular outlines but also to withstand the downward cutting thrust ofthe punch as it penetrates the stock and passes into the cooperatingdie.

Further objects of the invention are to provide a nibbling tool of thecharacter above described which is exceedingly simple and sturdy inconstmction and economical to manufacture and assemble, which has aminimum number of operating parts, and in which the punch and die'areeach readily accessible for replacement and repair as desired.

Other objects and advantages of the invention will appear more fullyhereinafter, it being understood that the invention consistssubstantially in the combination, construction, location and relativearrangement of parts, all as will be described more fully hereinafter,as shown in the accompanying drawing and as finally pointed out in theappended claims.

In the said accompanying drawing, which illustrates a preferredconstruction of the apparatus" of the present invention:

Figure 1 is a side view showing partly in elevation and partly invertical cross-section of a tool constructed in accordance with andembodying the principles of the present invention;

Figure 2 is a transverse view taken'on the line 2-2 of Figure 1;

Figure 3 is a transverse view taken along the line 33 of Figure 1;

Figure 4 is a horizontal sectional view taken along the line 44 ofFigure 1;

Figure 5 is a horizontal sectional view taken along the line 5-5 ofFigure 1;

Figure 6 is a horizontal sectional view taken along the line 6 6 ofFigure 1; and

Figure 7 is a bottom plan view of the relatively fixed support for thedie.

Referring now to the-drawing and more particularly to Figure 1 thereof,it will be observed that the nibbling tool of the present invention isof a form and constmction adapted to be conveniently held in the hand ofthe operator thereof, the operating head of the tool designatedgenerally by the reference numeral Ill being secured in any suitablemanner, as by a plurality of circumferentially spaced screws II, to theannular rim of the casing l2 in which is housed a conventional electricmotor l3 for operating the tool.

The operating head I!) of the tool includes a main body I! having arearwardly extending annular section I5 which is adapted to be securedby the screws lI-ll aforesaid or in any other suitable manner in axialalignment with the motor casing l2. The annular or cylindrical sectionI5 when so secured to the generally cylindrical motor housing I!thusprovides an elongated cylindrical body which may be convenientlygrasped in the hand during operation of the tool. It will be understood,of course, that if desired the said elongated cylindrical body formed bythe interconnected cylindrical parts l2 and I5 may be provided with asuitable handle (not shown), which handle may be of the form generallyprovided on other portable, hand-held electrically driven tools, such asdrills and .the like. It is preferable, however, to so design the saidcylindrical parts I 2 and I5 of the present. tool as to permit theunitary cylindrical casing or body to be conveniently grasped by thehand and so dispense with the need for any auxiliary handle.

As most clearly appears in Figure 1. the cylindrical section l5 of thetool is provided interiorly thereof with a longitudinally bored bearingboss I6 within which is jpurnalled the driven shaft ll of the tool.Rotation is imparted to this shaft H by a series of entrained gearsinterconnecting said driven shaft H with the shaft |8 of the motor. Asclearly appears in Figures 1 and 2, the inner end of the motor driveshaft |8 has fixed thereto a pinion gear l9, this gear l9 being in turnentrained with a larger intermediate gear 20. The gear 20 in turn isprovided upon its forward face with a coaxial small pinion gear 2| whichlatter is in turn entrained with the final driven gear 22. This latterdriven gear 22 is fixedly secured in any suitable manner to therearwardly projecting end of the shaft H which is journalled, asdescribed above, in a bearing boss l6 formed as an integral part of thecylindrical section |5. This bearing bore l6 preferably is in th form ofa solid semi-circular web extending across the upper half of the saidcylindrical section l and serves not only as a bearing for the shaft Hbut also as a bearing for a stub shaft 2|a (see Figure 2) upon which arejournalled, as a unit, the coaxial gears and 2|. The shaft I1 isprovided at its outer extremity with a forwardly extending eccentric 23which is fitted in a block or shoe 24.

Formed as an integral part of the cylindrical section |5 at th forwardextremity thereof is a front wall 25, the upper portion of which isrecessed, as at 26, to provide a vertically elongated groove or guidewayfor a purpose which will presentl appear. Along either side of thisrecess or guideway 26 are a pair of laterally spaced parallel flanges21-21 which project forwardly of the front face of the member 25. Theseflanges 21-21 ar preferably formed integrally with the member and extendfrom points adjacent the top of the tool casing as viewed in Figure 1 topoints adjacent the bottom of the tool casing. In other words, theseflanges 21-21 extend along chordal lines spaced equi-distantly to eitherside of the vertical diametric line of the front member 25 of the toolcasing, thus providing a pair of laterally spaced parallel guides for areciprocating member 28.

This reciprocating member 28 is provided in its upper part with arearwardly extending portion 29 which projects into the vertical grooveor recess 26 formed in the member 25. The rear face of the saidrearwardly projecting portion 29 of the reciprocating member 28 istransversely grooved, as at 30, to receive the block or shoe 24 which isfitted upon the eccentric 23. It will thus be apparent that as the shaft|1 rotates, the eccentric 23 shifts the block or shoe 24 laterallywithin the groove 30 simultaneously as said block or shoe acts on themember 28 to effect vertical reciprocation of the latter.

Formed as an integral part of the cylindrical section l5 of the tooloperating head and depending from the bottom of the forward closuremember 25 thereof is a part 3|. This part 3| is provided with a verticalchannel or groove 32 extending upwardly from the bottom thereof to apoint short of the top thereof, the said vertical groove beingrearwardly offset, as at 33. Adapted to be fitted in this verticalgroove of the member 3| is a support 33 for the lower die of the tool,it being observed that the said support 33 is se-' cured in positionwithin its accommodating groove 32 by means of the screws 34 which passthrough the body 3| from th rear face thereof into threaded engagementwith the said die support 33. The arrangement is such that as thesescrews 34-34 are tightened, the member 33 is drawn securely into itsgrooved seat 32 and therein rigidly and immovably supported.

As appears most clearly in Figures 1, 4' and 5, the front faces of thereciprocating member 28 and the di support 33 are respectively providedwith vertical grooves 35 and 36 arranged in vertical alignment one abovethe other. Disposed commonly in these grooves 35 and 36 is the squaredshank of a punch 31 which is secured to the reciprocating member 28 insuch manner that as the latter reciprocates it effects correspondingreciprocation of the punch 31.

As most clearly appears in Figures 1 and 4, the upper portion of thepunch 31 which is accommodated within the groove 35 is flrmly andimmovably clamped in said groove by means of a clamping plate 38 whichis secured to the reciprocating member 28 by the bolts or screws 38. Thlower portion of the punch 31 which is received within the groove 36 ofthe die support 33- is secured against, displacement from said groove 36by means of a front cover plate 46 which is secured to the body "3| bythe bolts 4|-4|. It will be noted in this connection that the said coverplate 40 does not-clampingly engage the lower portion of the punch 31but instead cooperates with the groove 36 in the die support 33 toprovide a vertical guide within which said punch is free to reciprocatein unison 'the said guid flanges 21-21 by means of bolts 43 (see Figure4). These retaining plates 42 overlap the vertical marginal edges of thereciprocating ram 28 sufficiently to prevent forward displacement of theram and at the same time permit free vertical reciprocatory movement ofsaid ram 28.

As appears in Figure 1, the upper part of the ram is horizontallynotched, as at 44, immediately above the upper end of the punch 31 andthreadedly receives an adjusting screw 45 arranged in verti;al alignmentwith said punch. The lower end of this adjusting screw 45 normallyengages the upper end of the punch 31 and serves as an upper abutmentthereof to prevent upward displacement of the punch at each impact ofthe punch against the metal being cut during the downward working strokeof the punch. The said adjusting screw 45 serves also as a means foradjusting the punch vertically along its reciprocating axis, it beingapparent that by adjusting the screw 45 in one direction or another apunch of given length may b positionally adjusted to present its cuttingedge in more or less closely spaced relation to the cooperating die forthe punch. g

Referring now again to the lower die support 33, it will be observedthat this support is formed at its lower end with a pair of laterallyspaced forwardly projecting arms 45-46. Bridging the upper surfaces ofthese arms isa die plate 41 which is secured in position by means ofscrews 48-48 projected upwardly through each of the arms 46 intothreaded engagement with the said die plate 41. As appears most clearlyin Figures 1 and 6, the said die plate 41 is centrally notched at itsrear edge, as at 49, in such manner that the three walls of said notch43 cooperate with the forward wall 50 of the die support 33 to provide arectangular die opening 5| into which the lower extremity of the punchis adapted to project as it penetrates the sheet material overlying thedie. In this connection, it will be noted that the lower extremity ofthe said punch 31 is ground to a rectangular shape corresponding to theshape of the said die opening L. operatively associated with th punch tostrip the sheet material therefrom when the punch is raised, is astripper 54, the purpose and operation of which are well understood inthe art.

It is important further to observe that the portion of the die support33 which projects freely below the body 3| is reduced in width, (seeparticularly Figures 2 and 6) so that its lateral thickness in the zoneof the working feeding plane is substantially equal to the width of thedie opening 5|. In other words, the portion 52 of the die support 33extending between the lower end of the body 3| and the upper surface ofthe die plate 41 is of a width substantially equal to the width of thecutting part of the punch 31. Also, it will be observed that the rearsurface of said portion 52 of the die support is rounded, as at 53. Byso shaping the said portion 52 of the die support in the vicinity of thefeeding plane of the sheet material to be cut, it becomes possible tocut a slot in the sheet material of a width equal to that of the punchand at the same time permit the tool as a whole to be more or lessfreely rotated in said slot to change the direction of the latter ascircumstances may require. Thus, the tool is adapted to slit the sheetmaterial along curved as well as straight lines. It will further beobserved that the overall dimensions of the die and its immediatelyassociated supporting structure are sufllciently small to permit thesame to be projected through a relatively small opening preliminarilyprovided in the sheet metal to be cut when it is desired to cut a designor outline in the sheet metal without passing through an edge thereof.Still .further, it will be observed that in the tool of thepresentconstruction reduced portion 52 of the die support 33 in its surfaceserves as a feed-limiting member or pilot to limit the feed of the. workas the latter isshifted relatively to the tool during the cuttingoperation. In addition, the said reduced portion 52 of the support 33backs up and so reinforces the lower cutting portion of the punch whichis of reduced cross-section and thus permits the use of a punch having arelatively thin cutting edge providing for an exceedingly small overlapon the material being cut. Thus, the bite of the punch on each downwardstroke thereof is sufliciently small to prevent jamming of the punch inthe work, to provide neat, smooth cuts and to enable the tool to beoperated at high speed. g

It will be understood, of course, that the invention is susceptible ofvarious changes and modifications which may be made from time to timewithout departing from the general principles or real spirit thereof andit is, accordingly, intended to claim the same broadly, as well asspecifically, as indicated by the appended claims.

What is claimed as new and useful is:

1. A portable self-contained motor-driven sheet metal cutting toolcomprising a main casing in which is housed the motor drive for thetool, said casing having an elongated guideway formed in its outer face,a vertically reciprocable ram fitted in said guideway and having alongitudinally extending groove therein for reception of a punch, meansintervening said motor drive and said ram for imparting reciprocation tosaid q ram by said motor drive, a die support detachably' disposed inspaced relation to said guideway, said die support being grooved inlongitudinal alignment with the ram groove and having a die openingtherein, and a punch fitted in said ram groove and arranged in axialalignment with said die opening for cooperation with the latter to cutsheet material fed between said reciprocating punch and its cooperatingdie, the groove in said die support terminating short of said dieopening and the die support in the immediate zone of the feeding planeof said material being of a thickness substantially equal to theeifective width of the punch and die opening.

2. In a motor-operated portable hand-held nibbling tool, a main casinghousing the motor drive for the tool, said casing being provided at oneend thereof with an elongated guideway, a ram disposed in said guideway,means interconnecting said ram and motor drive for effectingreciprocation of said ram in said guideway, a punch carried by andmovable with said ram, a portion of said punch being extended freelyfrom one extremity of said ram, a punch guide member rigid with saidcasing and arranged in spaced relation to said reciprocating ram andadapted to receive and guide the freely extending portion of said punch,a punch die operatively associated ciprocation along a line extendingtransversely of the casing means for effecting reciprocation of saidpunch, a fixed member for supporting a guide for the free extremity ofthe punch, a die operatively associated with the punch, and means forsupporting said die in fixed relation to said punch guide, said diesupporting means including an upper punch guiding part nested insaid-fixed member and a lower part with which the back face of thepunchsis in flatwise engagement and which, in the immediate zone of thefeeding plane of the sheet material to be cut, is of a width notexceeding the effective width of the punch.

4. In a motor-operated hand-held nibbling tool for slitting sheetmaterial, a main casing housing the motor drive for the tool, a punchdisposed at the forward end of said casing for reciprocation along aline extending transversely of the casing means for effectingreciprocation of said punch,

a fixed guide for the punch, a die operatively porting said die in fixedrelation to said punch guide, said die supporting means including asolid part immediately above the plane of said die which serves as areinforcing backing for the reciprocating punch and as a feed-limitingmember, and work stripping means arranged in spaced relation with saiddie and operatively associated with said punch to strip the same fromthe work upon each return stroke thereof.

5. In a motor-operated hand-held nibbling tool for slitting sheetmaterial, a main casing housing the motor drive for the tool, a guidewaydisposed at the forward end and extending transversely of said casing, aram slidably disposed in said guideway, means for effectingreciprocation of said ram in said guideway, a member fixedly associatedwith said casing at one extremity of said guideway, a die supportcarried by said member, said ram and said die support being providedwith longitudinally alined grooves for commonly receiving a punch, meansfixedly securing the upper part of" said punch in the ram groove, thelower part of the punch being freely slidable in the die support groove,means for retaining the ram against displacement from its said guideway,and means for retaining the reciprocating punch against displacementfrom its guiding groove in said die support.

6. In a motor-operated hand-held nibbling tool for slitting sheetmaterial, a main casing housing the motor drive for the tool, a punchdisposed at the forward end of said casing for reciprocation along aline extending transversely of the casing, means for effectingreciprocation of said punch, a relatively fixed channel-shaped guide forthe free extremity of said punch, said guide including as the base partthereof a detachable solid support for a die, and a die carried by saidsupport for cooperation with said punch, said detachable die supportbeing substantially L-shaped in longitudinal section and so disposedthat the longitudinal portion thereof serves as a backing for the punchand as a feed-limiting member, while the transverse portion thereofsupports the die in position extending transversely across thereciprocating axis of said punch.

'7. In a motor-operated hand-held nibbling tool for slitting sheetmaterial, a main casing housing the motor drive for the tool, a punchdisposed at the forward end of said casing for reciprocation along aline extending transversely of the casing, means for eifectingreciprocation of said punch, a relatively fixed channel-shaped guide forthe free extremity of said punch, said guide including as the base partthereof a detachable solid support for a die, and a die carried by saidsupport for cooperation with said punch, said detachable die supportserving commonly as a backing for the lower free extremity of thereciprocating punch, as a feed-limiting member and as the rear boundaryof the die opening, and work stripping means arranged in spaced relationwith said die and operatively associated with said punch to strip thesame from the work upon each return stroke thereof.

8. A tool of the character defined. in claim 7 including means foradjusting said punch axially with respect to said die. 4

9. A tool of the character defined in claim 7 including a reciprocatingram in which said punch is fixedly secured, and an adjusting screwmounted in said ram in axial alinement with said punch and engaging theupper end thereof, said screw serving as an upper fixed abutment forsaid punch. p

10. In a motor-operated portable hand-held nibbling tool, a main casinghousing the motor drive for the tool, a reciprocating ram disposed atthe forward end of said casing and adapted to be reciprocated by saidmotor drive, a punch fixedly associated with said ram and reciprocabletherewith, a channeled member fixedly associated with said casing anddisposed in longitudinally spaced relation with respect to said ram, adie support nested within and operatively associated with said channeledmember to provide a solid backing and guide for the free extremity ofthe reciprocating punch, said die support having a portion extendingfreely beyond said fixed member of a width not exceeding that of thepunch, and a die carried by said support for coaction with said punch.

11. In a motor-operated hand-held nibbling tool for slitting sheetmaterial, a main casing housing the motor drive for the tool, a punchdis-.

posed at the forward-end of said casing for reciprocation along a lineextending transversely of the casing, means for effecting reciprocationof said punch, a fixed member for supporting a guide for the freeextremity of the punch, a die operatively associated with the punch, andmeans serving commonly to guide the free extremity of the punch and tosupport said die in fixed relation to said punch-guide supportingmember, said die supporting means including a punch guiding part nestedin said fixed member and a punch backing part freely extending betweensaid die and said punch guiding part, said punch backing part having anoverall width not greater than the effective width of the punch and saiddie supporting means providing throughout its entire extent a solidbacking for the reciprocating punch.

CHARLES B. GRAY.

